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Ophthalmic Research
OPHTHALMIC RESEARCH Department EDITED BY FRANK W.
NEWELL,
M.D.
Abstracts of papers presented before the Western Section of the Association for Research in Ophthalmology, February 7, 1956, San Francisco, California A. RAY IRVINE, JR., M.D., Secretary, Western Section
The energy requirements of the lens: The ability of various metabolites to replace glucose as substrate. Daniel J. Heinrichs, B.S., and John E. Harris, M.D., Department of Ophthalmology, University of Oregon Medical School, Portland. The energy requirements of the lens ap pear to be largely provided by the metab olism of glucose. Knowledge of the path ways of glucose metabolism in the intact structure is yet incomplete. The classic Embden-Myerhof anaerobic glycolytic se quence has been demonstrated. However, the pathways by which oxygen is utilized are not known with any certainty, al though both the citric-acid cycle and the direct oxidative route have been postu lated. One of the major obstacles to the direct study of this problem is the low oxygen uptake. As an indirect approach we have studied an energy-utilizing mechanism, the cation pump, as an index of metabolic participation. When a lens is refrigerated at 0 ° C , potassium leaves the lens and sodium enters. During subsequent incuba tion at 37°C, potassium re-enters the lens and sodium is excreted from it. The rela tive ability of the lens to concentrate ca tions is considered to provide a measure of energy production. The cation pump has been shown to require oxygen. In the present experiments the ability to replace glucose of certain metabolites known to be intermediate in the major pathways already mentioned has been
studied. Under the conditions of the ex periment, we have found that small lenses may maintain a cation pump for some time without added glucose. Therefore, in these studies we have used lenses of a size that normally require added glucose. The sub strates employed have included lactate, pyruvate, acetate, citrate, oxaloacetate, alpha-keto glutarate, gluconate, and ribose. None of the compounds tested were able to replace glucose as substrate. (Cit rate proved to be quite toxic in the con centrations used, probably due to the binding of calcium, an ion which is essen tial for the maintenance of normal mem brane permeability.) The Excretion of Melanocyte-stimulating hormone by patients with certain ocular disorders. John E. Harris, M.D., and Aaron B. Lerner, M.D., Departments of Ophthalmology and Dermatology, Uni versity of Oregon Medical School, Port land. The melanocyte-stimulating hormone (MSH) is elaborated by the pituitary gland and can be found in detectable quan tities in human blood and urine.* Under its influence the skin darkens. Urinary ex cretion of the hormone is decreased in pi tuitary failure and after the administration of corticosteroids. It is increased in ad renal failure probably due to the un checked activity of the pituitary gland. * Shizume, K., and Lerner, A. B. : Determination of melanocyte-stimulating hormone in urine and Wood. J. Clin. Endocrinol. & Metab., 14:1491-1510, 1054. 537
538
OPHTHALMIC RESEARCH
This increase probably accounts for the pigmentation of Addison's disease. In certain instances, therefore, the melanocyte-stimulating hormone excretion can be taken as an index of the activity of the pituitary gland. + Melanocyte-stimulating hormone excre tion has been shown by others to be ele vated in individuals with retinitis pigmentosa. We have confirmed this finding in a relatively small group of patients in whom this diagnosis was permissible and in whom varying degrees of visual dis ability were noted. In our series, while the majority showed an elevated excretion of the hormone, in some the amount excreted was within the normal range. There ap peared to be no relationship between the visual disturbance or fundus picture and the melanocyte-stimulating excretion. In one patient with a choroideremia the melanocyte-stimulating hormone excre tion was elevated. However, the melano cyte-stimulating hormone output of his daughter, who showed a mottling of the pigment epithelium but no visual disturb ance, was normal. Melanocyte-stimulating hormone ex cretion was measured in a group of pa tients who, for various reasons, had had bilateral enucleations. These individuals showed a slightly elevated output, al though the excretion was not as high as was encountered in many other disturb ances. The most interesting group proved to be the patients with diabetic retinopathy. The majority of these patients had an ele vated melanocyte-stimuluating hormone excretion. By contrast, a group of diabetic individuals without retinopathy showed a normal output. The melanocyte-stimulat ing hormone excretion appeared to be more related to the duration of diabetes than to the degree of retinopathy or the degree of control. t Lerner, A. B., Shizume, K., and Bunding, I. : The mechanism of endocrine control of melanin pigmentation. J. Clin. Endocrinol. & Metab., 14:1463-1490, 1954.
Bovine vitreous filtrate. A. Suran, M.D., and W. K. McEwen, M.D., the Francis I. Proctor Foundation for Research in Ophthalmology, University of Califor nia Medical Center, San Francisco. Viscosity determinations on bovine vit reous filtrates at different age levels reveal an increase in viscosity with the growth of the eye. The possible filterlike action of the condensed outer layer of the vitreous was examined by permitting vitreous filtrate to drain through an exposed, un disturbed area of vitreous. Viscosities were measured on aliquots and it was found that the viscosities of the various fractions varied. The viral etiology of epidemic keratoconjunctivitis. E. Jawetz, M.D., P. Thygeson, M.D., L. Hanna, M.A., S. Kimura, M.D., and A. Nicholas, M.A., Depart ments of Microbiology and Ophthalmol ogy and the Francis I. Proctor Founda tion for Research in Ophthalmology, University of California Medical Center, San Francisco. A new member of the group of APC viruses has been isolated from a typical case of epidemic keratoconjunctivitis. Sera of patients with this disease show a strik ing rise in neutralizing and complementfixing antibodies to this virus. The results of a serologie survey from three conti nents suggest that this new virus is regu larly associated with epidemic keratocon junctivitis as it occurred in 1951-1955. Further studies concerning the activity of benzalkonium chloride against Pseudomonas aeruginosa. Sidney Riegelman and Daniel G. Vaughan, M.D., School of Pharmacy, Department of Ophtholmology, and the Francis I. Proctor Foundation for Research in Ophthal mology, University of California Medi cal Center, San Francisco. It was recently reported by C. A. Law rence that benzalkonium chloride (1 :
OPHTHALMIC RESEARCH 5,000) is a highly effective bactericidal agent against Pseudomonas aeruginosa. Since this contradicted our own experi mental results, tests were run in the Proc tor Laboratory on four strains obtained from Dr. Lawrence. Using the corneal infectivity test we found benzalkonium chloride (1:5,000) to be lacking in its bac tericidal effect against Pseudomonas aeru ginosa. However, in vitro results were in agreement with the findings of Dr. Law rence. A bacterial retentive filtering procedure. Sidney Riegelman and Daniel G. Vaughan, M.D., School of Pharmacy, Department of Ophthalmology, and the Francis I. Proctor Foundation for Re search in Ophthalmology, University of California Medical Center, San Fran cisco. A new filter membrane (Millipore Filter) incorporated in a Swinny filter adaptor has been proven to be completely retentive of bacteria and particulates of three microns or larger size. The assembly is attached to a hypodermic syringe, thus both filtering and sterilizing a solution with the application of a small amount of force on the plunger. This procedure is recommended as an additional safeguard in removing potential bacteria from an ophthalmic solution immediately prior to use in the eye during an operative pro cedure and in other dangerous situations. With the use of the present filter mem brane, the authors question the retention of virus particles. The technique of determination of blood volume changes in the choroid and ret ina. Victor G. Fellows, M.D., and J. W. Bettman, M.D., Stanford University, San Francisco. Until the present time there has never been a technique for determining changes in the total blood volume of the choroid and of the retina. In the past there have been many attempts to evaluate effects on
539
the blood vessels. These include direct observations of the blood vessels of the retina with the ophthalmoscope, with or without a graticule, photography with a Nordenson camera, photography with a slitlamp and Koeppe lens, and observation through the scierai window according to the technique of Leopold. Other methods include indirect estimation of the effects of change in vascularity through use of the electroretinogram by the technique of Henke, measurements of flicker-fusion frequency, and angioscotometry. None of these techniques permit estimation of the total blood volume of choroid and retina. The use of radioactive phosphorus per mits a direct measurement of changes in blood volume of the choroid and retina. The radioactive phosphorus is incubated with red blood cells after a blood speci men has been drawn from the animal. In cubation and gentle agitation are carried out for two hours, the plasma and buffer coat are removed by centrifuging, and the red cells are resuspended in saline and reinjected into the animal. Measurements of the radioactivity of the blood at intervals after such an injec tion indicate that the radioactive phos phorus remains in the blood stream for several hours. The vascularity of the sclera is negligible and that of the vitreous is nonexistent. Consequently, a GeigerMüller tube placed over the sclera behind the ora serrata gives an indication of the blood volume under that tube. This blood volume is almost entirely contained in the retina and choroid. Studies indicated great variation in blood flow unless there was control of the aeration of the animal. After intubating the animals and connecting them to a breathing machine, the results became constant. Variations in the carbon-dioxide and oxygen content resulted in changes in the blood volume. An evaluation of agents influencing the blood volume of the choroid and retina.
540
OPHTHALMIC RESEARCH
J. W. Bettman, M.D., and Victor G. Fellows, M.D., Stanford University, San Francisco. Using the radioisotope technique just reported, a systematic evaluation of agents which might affect the blood vol ume of the choroid and the retina was made. Certain vasodilators were entirely without effect ; others seemed to constrict the blood vessels of the choroid and retina. A new subconjunctival magnetic orbital implant. Orwyn H. Ellis, M.D., and O. Robert Levy, B.S., Los Angeles. In co-operation with the Magnet Di vision of General Electric Company an implant containing a magnet, the active poles of which end directly under Tenon's capsule and conjunctiva, has been de signed and produced. Since the magnetic force increases with the cube of the dis tance, to produce attraction, a magnet must be located as near as possible to the magnet in the prosthesis. This has been accomplished with this implant. The shape of the implant has been changed from a round back to a pyramid or cone. This has been found to rotate as well or better than the sphere, and has not turned in the orbit. The new implant appears larger but the volume is almost exactly the same. The movement of the finished prosthesis is as extensive or more ex tensive than that of previous implants, including the evisceration with implant. Paper electrophoresis as applied to the study of aqueous humor or other dilute ocular fluids. Ernest K. Goodner, the Francis I. Proctor Foundation for Re search in Ophthalmology, University of California Medical Center, San Fran cisco. The problem of the concentration of dilute protein solutions and the detection of the several protein fractions by paper electrophoresis near or at the limit of the method was investigated. If the protein concentration of the specimen is not at
least 0.5 percent or higher, the presence or absence of the several globulin frac tions cannot be definitely detected. Lysozyme in the tears of rabbits. S. J. Kimura, M.D., Lynette Feeney, and W. K. McEwen, M.D., the Francis I. Proctor Foundation for Research in Ophthalmology, University of Califor nia Medical Center, San Francisco. Ordinarily rabbit tears do not contain sufficient lysozyme to be detected by filter-paper electrophoresis. In a prelimi nary study it has been found that tears from an eye which is irritated or infected show lysozyme. The protein components of human tears. Robert Brunish, Ph.D., Department of Physiological Chemistry, School of Medicine, University of California, Los Angeles. Recently, McEwen and Kimura have employed filter-paper electrophoresis to separate the proteins present in tears. Their analysis showed the presence of at least three components in "normal" tears. One of these components was posi tively charged at pH 7.8 and was identi fied as lysozyme. Smollens, Leopold, and Parker, studying tears induced by a lacrimating agent, benzyl bromide, report the presence of four electrophoretic fractions, three of which were positively charged at pH 7.9. Caselli and Schumacher report the presence of five electrophoretic fractions, only one of which was positively charged at pH 8.6. In order to resolve these differences and to study the effect of irritants upon tear ing, different types of tears were com pared using filter-paper electrophoresis and, whenever possible, the 2.0 ml. Tiselius cell of the Spinco Model H apparatus. The paper strips were analyzed by em ploying the protein stain, bromophenol blue, which was eluted and analyzed colorimetrically. Emotional tears and tears pro duced in excessive amounts presumably
OPHTHALMIC RESEARCH through blockage of the nasolacrimal duct were considered "normal tears." No dif ference was found between these types of tears. The irritants used to produce tear ing were freshly cut onions and Los Angeles smog. Since the effects produced by the two irritants were similar, the re sults represent a summary of the two. Al though the globulins were resolved into two major and one minor components, they will be considered as one fraction. The average of 21 "normal" tear samples showed a percent distribution as follows : Albumin, 38.8 percent; globulin, 44.8 percent, and lysozyme, 16.4 percent. The 12 irritant-induced tear samples studied yielded values of 19.3, 54, and 26.7 percent. Exposure of normal tears to onion vapors did not change the composition suggesting that the irritant was not acting on the secreted fluid but was actually causing a different secretion to be formed. It is sug gested that the changed secretions may reflect a mechanism comparable to that seen in the double innervation of pancre atic or salivary gland secretion by hu moral and/or neural pathways. Some useful characteristics of the accom modation and convergence hyperbolas. Robert V. Hill, M.D., Department of Ophthalmology, University of Oregon Medical School, Portland. Accommodation and convergence hy perbolic equations were derived mathe matically and superimposed graphically for convenience of study of their normal and abnormal relationships. The common (and more solid) ground of an unequivocal mathematical expression of their normal relationships in all three variables (accom modation, convergence, and dioptric dis tance) provides a better background for study and discussion of abnormal rela tionships. Fixation disparity in relation to heterophoria. Arthur Jampolsky, M.D., Ber
541
nice Flom, O.D., and Allan Fried, O.D., Stanford University School of Medicine, San Francisco. Fixation disparity may be defined as the amount by which the visual axes miss intersection at the point of regard during conditions of single binocular vision. Single binocular vision is a more general statement of the binocular fusional proc ess but does not necessarily imply the more critical bifixation. Fixation disparity, therefore, is true bin ocular fusion with inexact bifoveal fusion, the fusion being maintained by perifoveal and more peripheral fusional areas of Panum. It is as if the foveas "were sitting on edge" and fusion exists by "the skin of the teeth." Fixation disparity is an ocular deviation occupying an intermediate sta tus between that of orthophoria with bi fixation and a manifest strabismus. It was the purpose of this study to measure fixation disparity in degree and character as it normally exists in patients exhibiting various degrees of heterophoria, under conditions simulating everyday visual situations. The experimental de sign had as its objective the binocular fusion of a large field of print with uni form peripheral as well as minute foveal fusionable detail. The error in exact bi foveal fusion (fixation disparity) was de termined by an optimally designed vernier alignment technique, utilizing monocularly presented, oppositely polarized, lines at the fixation area. Special attention was given to avoiding induced visual stress by lenses or prisms in order to measure quan titatively the fixation disparity normally occurring in a variety of heterophorias. The target design used at all times al lowed for the possibility of bifixation in that it is this error which was measured. It was hypothesized that the magnitude of fixation disparity would not signifi cantly vary with various degrees of exophoria, but would increase significantly and variably with increasing degrees of esophoria. This hypothesis was supported
542
OPHTHALMIC RESEARCH
by the evidence obtained in these experi ments. Ocular impedance, tissue heating, and scierai shrinkage in relation to electrosurgical treatment of retinal detach ment.* Henry A. Knoll, Ph.D., Depart ment of Biophysics, School of Medicine, University of California, Los Angeles. In order to understand better the effects of electrosurgical treatment of retinal de tachment on the eye, several fundamental aspects have been examined. Work to date has included measurement of ocular im pedance at various frequencies, measure ment of heat developed during the ap plication of electrosurgical treatment, the shrinkage during the application of electrosurgical treatment, and the shrink age characteristics of sclera and its effect upon intraocular pressure. Impedance measurements have been made at six frequencies between and in cluding 110 million cycles per second. Measurements were made on the eyes of anesthetized dogs and rabbits. The meas urements were made before and after sur face and puncture treatment. The results indicate little change in impedance after surface treatment but a drop in impedance after puncture. The drop is felt to be largely due to increased surface contact of the electrosurgical needle. A thermocouple placed in the choroid and vitreous of the eyes of anesthetized rabbits was used to measure the tempera ture rise during electrosurgical treatment. In general the temperature gradient sur rounding the needle is very steep and the heating effects are largely restricted to the external coats of the eye. Strips of sclera and cornea from re cently enucleated eyes of pigs and rabbits have been subjected to shrinkage meas urements. Critical temperatures between 60° to 65°C. are indicated at which un* Supported by a United States Public Health Service Grant. S. Rodman Irvine, M.D., and Wilbur A. Selle, Ph.D., chief investigators.
loaded tissue will contract to approxi mately one half of its initial length. The tissue stretches only slightly upon return to body temperatures. Changes in intraocular pressure as a result of electrosurgical treatment have been measured tonometrically in the eyes of anesthetized rabbits. Only a few surface treatments are required to double the intraocular pressure. Return to normal pressure required approximately one hour. Observations on the anatomy of the tra becular meshwork as seen in tangential section. Milton Flocks, M.D., Stanford University, School of Medicine, San Francisco. Increasing experimental evidence, sug gesting that the trabecular meshwork is the site of increased resistance to aqueous outflow in open-angle glaucoma, has fo cused interest on the histology and pathol ogy of this area. The meridional sections commonly used in eye pathology show only a lateral view of the meshwork which does not reveal its basic anatomy. Tangential views of the trabecular apparatus have been described from tissue which had been teased from the eye but such descriptions have not been reported of sections of the meshwork made in situ. A simple technique of mak ing tangential sections of the trabecula in situ has been devised. Using this method, a study of unused callottes from normal eyes of the Stanford Eye-Bank and of glaucomatous eyes from the Armed Forces Institute of Pathology and the Stanford University Eye Pathology Lab oratory is being made. The anatomy of the meshwork is seen to be strikingly more complex than when seen in ordinary meri dional sections. The openings of the corneoscleral mesh work, in contrast to the uveal meshwork, have a definite shape and alignment which may have physiologic significance. The distribution of the trabecular cells and of enmeshed pigment is of interest.
NEWELL,
M.D.
Abstracts of papers presented before the Western Section of the Association for Research in Ophthalmology, February 7, 1956, San Francisco, California A. RAY IRVINE, JR., M.D., Secretary, Western Section
The energy requirements of the lens: The ability of various metabolites to replace glucose as substrate. Daniel J. Heinrichs, B.S., and John E. Harris, M.D., Department of Ophthalmology, University of Oregon Medical School, Portland. The energy requirements of the lens ap pear to be largely provided by the metab olism of glucose. Knowledge of the path ways of glucose metabolism in the intact structure is yet incomplete. The classic Embden-Myerhof anaerobic glycolytic se quence has been demonstrated. However, the pathways by which oxygen is utilized are not known with any certainty, al though both the citric-acid cycle and the direct oxidative route have been postu lated. One of the major obstacles to the direct study of this problem is the low oxygen uptake. As an indirect approach we have studied an energy-utilizing mechanism, the cation pump, as an index of metabolic participation. When a lens is refrigerated at 0 ° C , potassium leaves the lens and sodium enters. During subsequent incuba tion at 37°C, potassium re-enters the lens and sodium is excreted from it. The rela tive ability of the lens to concentrate ca tions is considered to provide a measure of energy production. The cation pump has been shown to require oxygen. In the present experiments the ability to replace glucose of certain metabolites known to be intermediate in the major pathways already mentioned has been
studied. Under the conditions of the ex periment, we have found that small lenses may maintain a cation pump for some time without added glucose. Therefore, in these studies we have used lenses of a size that normally require added glucose. The sub strates employed have included lactate, pyruvate, acetate, citrate, oxaloacetate, alpha-keto glutarate, gluconate, and ribose. None of the compounds tested were able to replace glucose as substrate. (Cit rate proved to be quite toxic in the con centrations used, probably due to the binding of calcium, an ion which is essen tial for the maintenance of normal mem brane permeability.) The Excretion of Melanocyte-stimulating hormone by patients with certain ocular disorders. John E. Harris, M.D., and Aaron B. Lerner, M.D., Departments of Ophthalmology and Dermatology, Uni versity of Oregon Medical School, Port land. The melanocyte-stimulating hormone (MSH) is elaborated by the pituitary gland and can be found in detectable quan tities in human blood and urine.* Under its influence the skin darkens. Urinary ex cretion of the hormone is decreased in pi tuitary failure and after the administration of corticosteroids. It is increased in ad renal failure probably due to the un checked activity of the pituitary gland. * Shizume, K., and Lerner, A. B. : Determination of melanocyte-stimulating hormone in urine and Wood. J. Clin. Endocrinol. & Metab., 14:1491-1510, 1054. 537
538
OPHTHALMIC RESEARCH
This increase probably accounts for the pigmentation of Addison's disease. In certain instances, therefore, the melanocyte-stimulating hormone excretion can be taken as an index of the activity of the pituitary gland. + Melanocyte-stimulating hormone excre tion has been shown by others to be ele vated in individuals with retinitis pigmentosa. We have confirmed this finding in a relatively small group of patients in whom this diagnosis was permissible and in whom varying degrees of visual dis ability were noted. In our series, while the majority showed an elevated excretion of the hormone, in some the amount excreted was within the normal range. There ap peared to be no relationship between the visual disturbance or fundus picture and the melanocyte-stimulating excretion. In one patient with a choroideremia the melanocyte-stimulating hormone excre tion was elevated. However, the melano cyte-stimulating hormone output of his daughter, who showed a mottling of the pigment epithelium but no visual disturb ance, was normal. Melanocyte-stimulating hormone ex cretion was measured in a group of pa tients who, for various reasons, had had bilateral enucleations. These individuals showed a slightly elevated output, al though the excretion was not as high as was encountered in many other disturb ances. The most interesting group proved to be the patients with diabetic retinopathy. The majority of these patients had an ele vated melanocyte-stimuluating hormone excretion. By contrast, a group of diabetic individuals without retinopathy showed a normal output. The melanocyte-stimulat ing hormone excretion appeared to be more related to the duration of diabetes than to the degree of retinopathy or the degree of control. t Lerner, A. B., Shizume, K., and Bunding, I. : The mechanism of endocrine control of melanin pigmentation. J. Clin. Endocrinol. & Metab., 14:1463-1490, 1954.
Bovine vitreous filtrate. A. Suran, M.D., and W. K. McEwen, M.D., the Francis I. Proctor Foundation for Research in Ophthalmology, University of Califor nia Medical Center, San Francisco. Viscosity determinations on bovine vit reous filtrates at different age levels reveal an increase in viscosity with the growth of the eye. The possible filterlike action of the condensed outer layer of the vitreous was examined by permitting vitreous filtrate to drain through an exposed, un disturbed area of vitreous. Viscosities were measured on aliquots and it was found that the viscosities of the various fractions varied. The viral etiology of epidemic keratoconjunctivitis. E. Jawetz, M.D., P. Thygeson, M.D., L. Hanna, M.A., S. Kimura, M.D., and A. Nicholas, M.A., Depart ments of Microbiology and Ophthalmol ogy and the Francis I. Proctor Founda tion for Research in Ophthalmology, University of California Medical Center, San Francisco. A new member of the group of APC viruses has been isolated from a typical case of epidemic keratoconjunctivitis. Sera of patients with this disease show a strik ing rise in neutralizing and complementfixing antibodies to this virus. The results of a serologie survey from three conti nents suggest that this new virus is regu larly associated with epidemic keratocon junctivitis as it occurred in 1951-1955. Further studies concerning the activity of benzalkonium chloride against Pseudomonas aeruginosa. Sidney Riegelman and Daniel G. Vaughan, M.D., School of Pharmacy, Department of Ophtholmology, and the Francis I. Proctor Foundation for Research in Ophthal mology, University of California Medi cal Center, San Francisco. It was recently reported by C. A. Law rence that benzalkonium chloride (1 :
OPHTHALMIC RESEARCH 5,000) is a highly effective bactericidal agent against Pseudomonas aeruginosa. Since this contradicted our own experi mental results, tests were run in the Proc tor Laboratory on four strains obtained from Dr. Lawrence. Using the corneal infectivity test we found benzalkonium chloride (1:5,000) to be lacking in its bac tericidal effect against Pseudomonas aeru ginosa. However, in vitro results were in agreement with the findings of Dr. Law rence. A bacterial retentive filtering procedure. Sidney Riegelman and Daniel G. Vaughan, M.D., School of Pharmacy, Department of Ophthalmology, and the Francis I. Proctor Foundation for Re search in Ophthalmology, University of California Medical Center, San Fran cisco. A new filter membrane (Millipore Filter) incorporated in a Swinny filter adaptor has been proven to be completely retentive of bacteria and particulates of three microns or larger size. The assembly is attached to a hypodermic syringe, thus both filtering and sterilizing a solution with the application of a small amount of force on the plunger. This procedure is recommended as an additional safeguard in removing potential bacteria from an ophthalmic solution immediately prior to use in the eye during an operative pro cedure and in other dangerous situations. With the use of the present filter mem brane, the authors question the retention of virus particles. The technique of determination of blood volume changes in the choroid and ret ina. Victor G. Fellows, M.D., and J. W. Bettman, M.D., Stanford University, San Francisco. Until the present time there has never been a technique for determining changes in the total blood volume of the choroid and of the retina. In the past there have been many attempts to evaluate effects on
539
the blood vessels. These include direct observations of the blood vessels of the retina with the ophthalmoscope, with or without a graticule, photography with a Nordenson camera, photography with a slitlamp and Koeppe lens, and observation through the scierai window according to the technique of Leopold. Other methods include indirect estimation of the effects of change in vascularity through use of the electroretinogram by the technique of Henke, measurements of flicker-fusion frequency, and angioscotometry. None of these techniques permit estimation of the total blood volume of choroid and retina. The use of radioactive phosphorus per mits a direct measurement of changes in blood volume of the choroid and retina. The radioactive phosphorus is incubated with red blood cells after a blood speci men has been drawn from the animal. In cubation and gentle agitation are carried out for two hours, the plasma and buffer coat are removed by centrifuging, and the red cells are resuspended in saline and reinjected into the animal. Measurements of the radioactivity of the blood at intervals after such an injec tion indicate that the radioactive phos phorus remains in the blood stream for several hours. The vascularity of the sclera is negligible and that of the vitreous is nonexistent. Consequently, a GeigerMüller tube placed over the sclera behind the ora serrata gives an indication of the blood volume under that tube. This blood volume is almost entirely contained in the retina and choroid. Studies indicated great variation in blood flow unless there was control of the aeration of the animal. After intubating the animals and connecting them to a breathing machine, the results became constant. Variations in the carbon-dioxide and oxygen content resulted in changes in the blood volume. An evaluation of agents influencing the blood volume of the choroid and retina.
540
OPHTHALMIC RESEARCH
J. W. Bettman, M.D., and Victor G. Fellows, M.D., Stanford University, San Francisco. Using the radioisotope technique just reported, a systematic evaluation of agents which might affect the blood vol ume of the choroid and the retina was made. Certain vasodilators were entirely without effect ; others seemed to constrict the blood vessels of the choroid and retina. A new subconjunctival magnetic orbital implant. Orwyn H. Ellis, M.D., and O. Robert Levy, B.S., Los Angeles. In co-operation with the Magnet Di vision of General Electric Company an implant containing a magnet, the active poles of which end directly under Tenon's capsule and conjunctiva, has been de signed and produced. Since the magnetic force increases with the cube of the dis tance, to produce attraction, a magnet must be located as near as possible to the magnet in the prosthesis. This has been accomplished with this implant. The shape of the implant has been changed from a round back to a pyramid or cone. This has been found to rotate as well or better than the sphere, and has not turned in the orbit. The new implant appears larger but the volume is almost exactly the same. The movement of the finished prosthesis is as extensive or more ex tensive than that of previous implants, including the evisceration with implant. Paper electrophoresis as applied to the study of aqueous humor or other dilute ocular fluids. Ernest K. Goodner, the Francis I. Proctor Foundation for Re search in Ophthalmology, University of California Medical Center, San Fran cisco. The problem of the concentration of dilute protein solutions and the detection of the several protein fractions by paper electrophoresis near or at the limit of the method was investigated. If the protein concentration of the specimen is not at
least 0.5 percent or higher, the presence or absence of the several globulin frac tions cannot be definitely detected. Lysozyme in the tears of rabbits. S. J. Kimura, M.D., Lynette Feeney, and W. K. McEwen, M.D., the Francis I. Proctor Foundation for Research in Ophthalmology, University of Califor nia Medical Center, San Francisco. Ordinarily rabbit tears do not contain sufficient lysozyme to be detected by filter-paper electrophoresis. In a prelimi nary study it has been found that tears from an eye which is irritated or infected show lysozyme. The protein components of human tears. Robert Brunish, Ph.D., Department of Physiological Chemistry, School of Medicine, University of California, Los Angeles. Recently, McEwen and Kimura have employed filter-paper electrophoresis to separate the proteins present in tears. Their analysis showed the presence of at least three components in "normal" tears. One of these components was posi tively charged at pH 7.8 and was identi fied as lysozyme. Smollens, Leopold, and Parker, studying tears induced by a lacrimating agent, benzyl bromide, report the presence of four electrophoretic fractions, three of which were positively charged at pH 7.9. Caselli and Schumacher report the presence of five electrophoretic fractions, only one of which was positively charged at pH 8.6. In order to resolve these differences and to study the effect of irritants upon tear ing, different types of tears were com pared using filter-paper electrophoresis and, whenever possible, the 2.0 ml. Tiselius cell of the Spinco Model H apparatus. The paper strips were analyzed by em ploying the protein stain, bromophenol blue, which was eluted and analyzed colorimetrically. Emotional tears and tears pro duced in excessive amounts presumably
OPHTHALMIC RESEARCH through blockage of the nasolacrimal duct were considered "normal tears." No dif ference was found between these types of tears. The irritants used to produce tear ing were freshly cut onions and Los Angeles smog. Since the effects produced by the two irritants were similar, the re sults represent a summary of the two. Al though the globulins were resolved into two major and one minor components, they will be considered as one fraction. The average of 21 "normal" tear samples showed a percent distribution as follows : Albumin, 38.8 percent; globulin, 44.8 percent, and lysozyme, 16.4 percent. The 12 irritant-induced tear samples studied yielded values of 19.3, 54, and 26.7 percent. Exposure of normal tears to onion vapors did not change the composition suggesting that the irritant was not acting on the secreted fluid but was actually causing a different secretion to be formed. It is sug gested that the changed secretions may reflect a mechanism comparable to that seen in the double innervation of pancre atic or salivary gland secretion by hu moral and/or neural pathways. Some useful characteristics of the accom modation and convergence hyperbolas. Robert V. Hill, M.D., Department of Ophthalmology, University of Oregon Medical School, Portland. Accommodation and convergence hy perbolic equations were derived mathe matically and superimposed graphically for convenience of study of their normal and abnormal relationships. The common (and more solid) ground of an unequivocal mathematical expression of their normal relationships in all three variables (accom modation, convergence, and dioptric dis tance) provides a better background for study and discussion of abnormal rela tionships. Fixation disparity in relation to heterophoria. Arthur Jampolsky, M.D., Ber
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nice Flom, O.D., and Allan Fried, O.D., Stanford University School of Medicine, San Francisco. Fixation disparity may be defined as the amount by which the visual axes miss intersection at the point of regard during conditions of single binocular vision. Single binocular vision is a more general statement of the binocular fusional proc ess but does not necessarily imply the more critical bifixation. Fixation disparity, therefore, is true bin ocular fusion with inexact bifoveal fusion, the fusion being maintained by perifoveal and more peripheral fusional areas of Panum. It is as if the foveas "were sitting on edge" and fusion exists by "the skin of the teeth." Fixation disparity is an ocular deviation occupying an intermediate sta tus between that of orthophoria with bi fixation and a manifest strabismus. It was the purpose of this study to measure fixation disparity in degree and character as it normally exists in patients exhibiting various degrees of heterophoria, under conditions simulating everyday visual situations. The experimental de sign had as its objective the binocular fusion of a large field of print with uni form peripheral as well as minute foveal fusionable detail. The error in exact bi foveal fusion (fixation disparity) was de termined by an optimally designed vernier alignment technique, utilizing monocularly presented, oppositely polarized, lines at the fixation area. Special attention was given to avoiding induced visual stress by lenses or prisms in order to measure quan titatively the fixation disparity normally occurring in a variety of heterophorias. The target design used at all times al lowed for the possibility of bifixation in that it is this error which was measured. It was hypothesized that the magnitude of fixation disparity would not signifi cantly vary with various degrees of exophoria, but would increase significantly and variably with increasing degrees of esophoria. This hypothesis was supported
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by the evidence obtained in these experi ments. Ocular impedance, tissue heating, and scierai shrinkage in relation to electrosurgical treatment of retinal detach ment.* Henry A. Knoll, Ph.D., Depart ment of Biophysics, School of Medicine, University of California, Los Angeles. In order to understand better the effects of electrosurgical treatment of retinal de tachment on the eye, several fundamental aspects have been examined. Work to date has included measurement of ocular im pedance at various frequencies, measure ment of heat developed during the ap plication of electrosurgical treatment, the shrinkage during the application of electrosurgical treatment, and the shrink age characteristics of sclera and its effect upon intraocular pressure. Impedance measurements have been made at six frequencies between and in cluding 110 million cycles per second. Measurements were made on the eyes of anesthetized dogs and rabbits. The meas urements were made before and after sur face and puncture treatment. The results indicate little change in impedance after surface treatment but a drop in impedance after puncture. The drop is felt to be largely due to increased surface contact of the electrosurgical needle. A thermocouple placed in the choroid and vitreous of the eyes of anesthetized rabbits was used to measure the tempera ture rise during electrosurgical treatment. In general the temperature gradient sur rounding the needle is very steep and the heating effects are largely restricted to the external coats of the eye. Strips of sclera and cornea from re cently enucleated eyes of pigs and rabbits have been subjected to shrinkage meas urements. Critical temperatures between 60° to 65°C. are indicated at which un* Supported by a United States Public Health Service Grant. S. Rodman Irvine, M.D., and Wilbur A. Selle, Ph.D., chief investigators.
loaded tissue will contract to approxi mately one half of its initial length. The tissue stretches only slightly upon return to body temperatures. Changes in intraocular pressure as a result of electrosurgical treatment have been measured tonometrically in the eyes of anesthetized rabbits. Only a few surface treatments are required to double the intraocular pressure. Return to normal pressure required approximately one hour. Observations on the anatomy of the tra becular meshwork as seen in tangential section. Milton Flocks, M.D., Stanford University, School of Medicine, San Francisco. Increasing experimental evidence, sug gesting that the trabecular meshwork is the site of increased resistance to aqueous outflow in open-angle glaucoma, has fo cused interest on the histology and pathol ogy of this area. The meridional sections commonly used in eye pathology show only a lateral view of the meshwork which does not reveal its basic anatomy. Tangential views of the trabecular apparatus have been described from tissue which had been teased from the eye but such descriptions have not been reported of sections of the meshwork made in situ. A simple technique of mak ing tangential sections of the trabecula in situ has been devised. Using this method, a study of unused callottes from normal eyes of the Stanford Eye-Bank and of glaucomatous eyes from the Armed Forces Institute of Pathology and the Stanford University Eye Pathology Lab oratory is being made. The anatomy of the meshwork is seen to be strikingly more complex than when seen in ordinary meri dional sections. The openings of the corneoscleral mesh work, in contrast to the uveal meshwork, have a definite shape and alignment which may have physiologic significance. The distribution of the trabecular cells and of enmeshed pigment is of interest.